Hyperboloid electrical contacts or contact sockets are known for their reliability, resistance to vibration, low insertion force, low electrical resistance and high number of insertion/extraction cycles. A conventional hyperboloid contact socket is depicted in FIG. 1 and includes an inner tubular sleeve which is open at both ends and which is located coaxially within two cylindrical sections that form an outer shell. The distal end of one of the outer sections is machined to form a cavity for permanently affixing wires to the contact either by soldering or crimping. Alternatively the distal end can be machined to form a pin to be soldered or press fit into a circuit board, or used to affix wires by wrapping them onto the pin. The proximal end of the second outer cylindrical section remains open to receive the male pin of a mating connector or device. A plurality of loose, or floating wires is arrayed within the inner sleeve to form the shape of a single sheet hyperboloid. At each end of the inner sleeve the wires are bent 180 degrees outward so as to return axially between the inner and outer sleeves. The wire ends are thereby retained at each end of the inner sleeve by means of a press fit between the wires and the inner and outer sleeves as shown in the prior art FIG. 1. Rolling, crimping, swaging or other suitable means to provide mechanical and conductive attachment is used to affix the outer sleeves at or near the axial midpoint of the inner sleeve. This contact configuration has been in use for many years and is known to present a difficult assembly task and to require expensive, high precision machined components. Additionally, due to the nature of the press fit retention of the wires, it is not uncommon for the wires to become separated from within the inner and outer sleeves, particularly during usage of the contact, thereby leading to field failures of the device in which it is in use. Additionally, this type of field failure can lead to damage of the mating male connector elements, further exacerbating the extent and cost of repair of the overall system in which the contact has been deployed. In addition, because of the concentric arrangement of the inner and outer cylindrical sections and the retained contact wires, the contact structure is larger in diameter than other forms of contacts and cannot therefore be used in applications requiring higher contact density, or in applications requiring the characteristics set forth above where miniaturization must be realized. Examples of the foregoing prior art are shown in U.S. Pat. Nos. 3,107,966, 3,229,356, 3,470,527 and 6,102,746.
More recently hyperboloid contact sockets have been developed which can be manufactured using automated high speed manufacturing processes wherein different types of terminations can be affixed to the contact socket as desirable for user requirements. This type of hyperboloid contact socket is depicted in FIG. 2 and is described in U.S. Pat. No. 6,767,260 which is owned by the assignee of the present application. The socket includes a tubular body 20, one end of which has a lip 22 defining an entrance aperture 24 for receiving a mating pin. The tubular body 20 contains a plurality of conductive wires 28 welded or otherwise conductively and permanently affixed at their respective ends to the inner surface of the tubular body at respective ends of the body and disposed in an angular disposition with respect to the longitudinal axis to form a hyperboloid shape. The tubular body 20 is attached to a termination 26 at a junction 27 by rolling, crimping, swaging or other suitable means to provide mechanical and conductive attachment.
The socket is formed via use of a mandrel having a plurality of spaced longitudinal wire receiving grooves. Wires are inserted within the grooves of the mandrel and the wires are inserted into the tubular body to the point at which the wires abut the inner annular surface of the lip. The upper ends of the wires are permanently affixed, preferably by laser welding or other suitable means, to the confronting inner wall portion of the tubular body adjacent the lip.
The mandrel is then partially withdrawn and rotated with respect to the body by a predetermined angular extent to produce an angular orientation of the wires and the lower end of the wires are conductively and permanently affixed to the confronting wall portion of the tubular body, preferably by laser welding, or other suitable means, and the body and the mandrel are thereafter separated. The resultant body has the wires angularly disposed within the body so as to form a hyperboloid shape which accommodates and provides electrical engagement with a terminal pin that is inserted into the contact socket through the aperture 24. This type of hyperboloid contact socket offers the advantages of a smaller diameter, reduction in the number of machined components and suitability for automated high speed manufacture when compared to earlier hyperboloid contacts.
In one embodiment disclosed in U.S. Pat. No. 6,767,260, one end of the mandrel is affixed to the body and a termination is affixed to the other end of the mandrel as illustrated in FIG. 3. One problem for this type of hyperboloid socket contact is that the overall length of the contact is increased due to the presence of the mandrel in the assembled socket. This makes the contact unsuitable for high density applications requiring a short contact, such as would be the case in printed circuit board connectors or in connectors where axial space is limited. In addition, this type of contact could be reduced in diameter still further, allowing for greater contact density, if it were not necessary to provide for terminations to be attached to the outside diameter of the mandrel as shown in FIG. 3. Examples of the foregoing prior art are shown in U.S. Pat. Nos. 6,767,260 and 7,191,518 which are assigned to the assignee of the present application.
It would be useful to provide a hyperboloid contact socket having a shorter overall length to permit its use in printed circuit board connector applications. It would also be useful to provide a hyperboloid contact socket having a smaller outside diameter to permit use in applications requiring closer center distance spacing. It would also be useful to reduce the cost of manufacturing through the elimination of unnecessary parts and through improvement in the efficiency of assembly by permanent and conductive attachment of the contact wires into position within a contact body to form the hyperboloid contact area. It would also be useful to provide a contact socket where the need for costly machined components is reduced or eliminated.